The invention relates to a formwork comprising a plurality of interconnectable formwork elements for the casting of especially walls and similar constructions, and otherwise of the kind that are substantially cylindrically-formed, thin-walled, self-supporting and preferably flexible. The invention also involves a method for the use of said formwork elements, and in particular to method for the casting of walls and similar constructions using the formwork.
Casting of e.g. foundations, sustaining walls, walls, pavement or roof in concrete or similar hardenable filling materials by means of formwork elements in the form of wooden panels is laborious and time-consuming. Such formwork panels are heavy and awkward; they have to be transported on crane vehicle and require binders, the necessary working operations comprising carrying, erecting, removal, oiling (lubrication) and storage of the panels.
Likewise, finished brick blocks and elements require much treatment in factory, costly transport, laborious erecting and comprehensive after-treatment.
The prior art comprises also Norwegian patent specification No. 46,428, DE-OS 2,213,358, DE-AS 1,684,357, U.S. Pat. No. 2,184,714, DE, C2, 3 234 489, DE, A1, 3 727 956, WO, A1, 82/04088, DE, A, 1 812 590, DE, C2, 3 003 446, SE, 206 538 as well as FR-A-1 603 005.
NO-PS 46,428 relates to a pile blanking consisting of hollow interconnectable sections. Substantially as a result of the design of the connecting means of this known pile blanking, the pile blanking will--used as a formwork--only be usable for the casting of spaced columns; on the other hand it will not enable casting of a continuous wall, or permit reinforcing using horizontal and/or diagonally extending reinforcing rods. However, between adjacent sections or elements it is from this patent specification known per se to use mutually cooperating coupling means adapted to be brought into firmly maintaining engagement with each other.
DE-OS 2,213,358 relates to a flexible, reinforced formwork cloth which is not self-supporting, but has to be used in combination with suitable walls of timber placed endwise and, thus, exhibiting substantially the same disadvantages as panel formworks.
DE-AS 1,684,357 relates also to a flexible, reinforced, not self-supporting formwork cloth divided into interconnectable sections, which can be connected mutually by means of connecting means adapted to be brought into firmly maintaining engagement with each other. This prior art formwork system does not permit casting of continuous walls and, moreover, prohibits the arrangement of crossing reinforcing rods.
U.S. Pat. No. 2,184,714 does not relate to formwork, but concerns casted pre-reinforced concrete elements. When such concrete elements or blocks are being used for building purposes, locking rods are used for keeping adjacent concrete blocks in place in the finished construction.
DE, C2, 3 234 489. This prior art structure and that of the above-mentioned Norwegian patent specification No. 46 428 resemble each other in many respects. In the embodiments shown, this construction is not suitable to be used as a formwork.
DE, A1, 3 727 956 discloses formwork elements made of light (weight) concrete and adapted to be glued together. In many respects these prior art elements, though elongated, resemble the well known concrete blocks previously discussed.
WO, A1, 82/04088 discloses methods for the building of constructions and comprises a "stay-in-place" formwork for concrete casting. The formwork elements are not self-supporting, and the erected formwork structure constitutes, in fact, a conventional thick-walled formwork requiring the use of i.e. ordinary binders.
DE, A, 1 812 590 discloses building elements; the entire formwork structure requiring elements of several different shapes. These differently shaped elements are to be kept together by tensioning means, thereby involving the use of a rather large number of loose parts.
DE, C2, 3 003 446 discloses formwork elements of the block type previously discussed and suffering from the very same drawbacks and disadvantages.
SE, 206 538 discloses hollow building or construction plates having neither mutually communicating cavities defined by adjacent plates nor protruding cooperating locking connecting means of the kind in question.
FR, A, 1 603 005 discloses a formwork having two opposing pliable walls and which may be prefabricated. The pliable walls of this prior art formwork are formed by a plurality of substantially tubular interconnectable thin-walled formwork elements exhibiting a generally C-shaped cross-sectional profile. When interconnected, a longitudinal portion of one formwork element of adjacent pairs forms a laterally extending, non-apertured, common partition wall for the pair of adjacent formwork elements. In the preferred embodiment, these prior art formwork elements are made from pliable cloth or canvas materials, leaving the elements non-self-supporting. However, in one extreme embodiment, this prior art publication suggests to make the formwork elements from flexible rolled metal plate, and in that case the formwork elements would, of course, be self-supporting. According to this French patent specification, the following methods are mentioned as being suitable for the interconnection of the tubular elements: Sewing, adhesion and welding.
The formwork elements according to FR, A, 1 603 005 lack intercommunicating apertures allowing free flow of concrete and, according to the French specification, the spaces surrounded by each one of the elements plus the partition wall of the neighbour element are to be filled successively. Before casting can take place, the interconnected elements have to be fixed or suspended between an upper and a lower fixture. This and the mentioned interconnection methods makes this prior art formwork difficult to erect, as well as the casting process being complicated. The lack of intercommunicating apertures throughout the erected formwork prohibits the use of internal, horizontally and/or diagonally extending reinforcing rods. In its self-supporting embodiment, the tubular formwork elements of rolled metal plate will be space-demanding during transport and storage.
According to the present invention one has aimed at providing a formwork system consisting of self-supporting interconnectable disposable formwork elements capable of being connected mutually in order to form especially a wall formwork, wherein the concrete or another hardenable filling material during the filling operation may flow freely between the interconnected formwork elements, so that the result becomes a continuous construction which--when the formwork is kept (not removed)--becomes coated with its material, e.g. plastic.
Likewise, one has aimed at eliminating or substantially restricting disadvantages and drawbacks in prior art formwork systems.